1. Field of the Invention
The present invention relates generally to a dual technology glass breakage detector, and more particularly pertains to a dual technology glass breakage detector for a security system that includes an acoustic sensor/audio processor for detecting a sound of breaking glass of a glass window or door, and also a second impact sensor mounted on the glass window or door to verify that there was a physical/mechanical impact to the glass window or door before the security system annunciates an alarm signal.
2. Discussion of the Prior Art
The present invention addresses the commercial problem of a security system, such as a commercial or residential/home security system, providing a glass breakage sensor for detecting an intrusion into a protected space through a glass window or door. Existing prior art glass breakage sensors designed to detect the breakage of glass windows or doors are problematic.
One current state of the art glass breakage sensor employs a microphone and an audio processor, typically strategically mounted on a ceiling, to monitor sounds within a protected space to determine if glass in a glass window or door has been broken. A problem with this arrangement is that sounds other than those of breaking glass from a glass window or door can fool the audio processor and cause the issuance of a false alarm by the security system. Some examples of sounds that can fool the audio processor and cause the issuance of false alarms include sounds of a barking dog, the popping of a balloon, a dropping of a pot or pan, an accidental dropping and breakage of a drinking glass, and the closing of a kitchen cabinet.
The present invention provides a dual technology glass breakage detector that solves the prior art problem of acoustic glass breakage detectors issuing false alarms by using a second impact sensor to verify that the window or door also experienced a mechanical/physical impact. Sounds within the protected space that would normally fool a prior art glass breakage detector usually do not transfer significant mechanical energy to the glass window or door. Pursuant to the present invention, for an alarm to be annunciated, the acoustic sensor must detect the sound of breaking glass, and also a second impact sensor on the glass window or door must verify that there was a physical/mechanical impact to the glass window or door.